For a crawlspace, you can either insulate the floor cavity between the crawl and the home (the crawl space is still unconditioned), or you can insulate the walls of the crawlspace (the crawl space is now conditioned).
Insulating the floor cavity, Unconditioned Crawl
For the improved energy value, choose Unconditioned Crawl. That will open the floor cavity insulation option, edit the R Value to your specifications.
Insulating the walls of the crawl space, Conditioned Crawl.
For the improved energy values, choose Conditioned Crawl. This will open up the Wall Insulation option, and includes sealing off any vents to the outside, insulating the foundation walls, and installing a vapor barrier on top of the dirt floor.
It is not an option to both insulate the walls and insulate the floor cavity. If the crawl space is conditioned (insulated) then the floor cavity no longer needs to be insulated.
Additional Info -
Some users may experience low or even negative savings numbers by creating a conditioned crawlspace from an unconditioned crawlspace. While this may seem wrong to you, it’s actually likely that the number is correct. Before we go further, we agree that conditioning a crawlspace is a best practice and is beneficial for many reasons:
Cold outside air is no longer circulating underneath the home, therefore eliminating “cold feet in the kitchen” syndrome.
Ductwork and HVAC equipment that was formerly in an unconditioned space is now in a conditioned space
Air leakage through the floor of the home can be dramatically reduced
Sometimes, significant energy savings can be achieved
So, how is it that energy savings isn’t always achieved? If you change an unconditioned crawl to a conditioned crawl by moving the insulation to the walls, you're actually increasing the total square footage of surface area exposed to the outside. For a relatively small crawlspace, this will often increase the conductive losses of the space. Outside ground temperatures (calculated regionally by our software), as well as the outside air temperatures have a large play in this.
In the end, the Insulate Crawlspace recommendation in Snugg Pro only reflects energy savings associated with the conductive losses of that space plus any savings from duct work being moved into conditioned space as a result. The total energy consumption of the crawl space could feasibly increase by adding this additional space even though you're increasing the R-value of insulation. All of the benefits of reduced air leakage need to be reflected in the reduced CFM50 in the Seal Air Leaks recommendation.
But don't forget the most important reason to do this is comfort. The key is to talk about it as a holistic approach to increased comfort and total energy savings.